Mockito在Spring测试类@BeforeAll方法中抛出NPE

Question

@SpringBootTest
@AutoConfigureMockMvc(addFilters = false)
public class VirtualMachineServiceIntegrationTests {

    @MockBean
    static VirtualMachineService virtualMachineService;

    @Autowired
    private MockMvc mockMvc;
    @Autowired
    private ObjectMapper objectMapper;

    static String courseId;
    static String studentId;
    static Long teamId;
    static Long vmId;
    static SystemImage os;
    static VirtualMachineDTO virtualMachineDTO;
    static ConfigurationDTO configurationDTO;


    @BeforeAll
    static void beforeAll() {
        studentId = "student";
        courseId = "course";
        teamId = 1L;
        vmId = 1L;
        os = SystemImage.WINDOWS_10;
        virtualMachineDTO = VirtualMachineDTO.builder()
                .id(1L)
                .num_vcpu(2)
                .disk_space(1000)
                .ram(4)
                .status(VirtualMachineStatus.OFF)
                .build();
        configurationDTO = ConfigurationDTO.builder()
                .id(1L)
                .min_vcpu(2)
                .min_disk(1000)
                .min_ram(4)
                .max_vcpu(12)
                .max_disk(2000)
                .max_ram(16)
                .max_on(4)
                .tot(20)
                .build();

        Mockito.when(Mockito.any(VirtualMachineService.class).createVirtualMachine(Mockito.anyString(), Mockito.anyLong(), Mockito.anyString(), Mockito.anyInt(), Mockito.anyInt(), Mockito.anyInt())).thenReturn(virtualMachineDTO);
    }
}

 Mockito.when(Mockito.any(VirtualMachineService.class).createVirtualMachine(Mockito.anyString(), Mockito.anyLong(), Mockito.anyString(), Mockito.anyInt(), Mockito.anyInt(), Mockito.anyInt())).thenReturn(virtualMachineDTO);

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Misplaced or misused argument matcher detected here:

-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)
-> at it.polito.ai.backend.VirtualMachineServiceIntegrationTests.createVirtualMachine(VirtualMachineServiceIntegrationTests.java:87)

You cannot use argument matchers outside of verification or stubbing.
Examples of correct usage of argument matchers:
    when(mock.get(anyInt())).thenReturn(null);
    doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject());
    verify(mock).someMethod(contains("foo"))

This message may appear after an NullPointerException if the last matcher is returning an object 
like any() but the stubbed method signature expect a primitive argument, in this case,
use primitive alternatives.
    when(mock.get(any())); // bad use, will raise NPE
    when(mock.get(anyInt())); // correct usage use

Also, this error might show up because you use argument matchers with methods that cannot be mocked.
Following methods *cannot* be stubbed/verified: final/private/equals()/hashCode().
Mocking methods declared on non-public parent classes is not supported.

Answer 1

这里有很多事情有点奇怪。主要/误解问题是：

mockito#when用于告诉具体的mock在特定的方法调用上做什么。所以通常情况下是这样的：

Mockito.when(mock.doSomeThings(anyString()).thenReturn("whatever");

将此模式应用到代码中，应该可以实现以下目的：

Mockito.when(virtualMachineService.createVirtualMachine(Mockito.anyString(), Mockito.anyLong(), Mockito.anyString(), Mockito.any Int(), Mockito.anyInt(), Mockito.anyInt())).thenReturn(virtualMachineDTO);